Light waves oscillate perpendicular to their direction of travel. Polarization is the orientation of those oscillations. Unpolarized light, like sunlight, oscillates in all directions. Polarized light oscillates in a single plane. Polarizing filters block light that oscillates in certain directions and transmit light that oscillates in others. That is how polarized sunglasses reduce glare. Glare is light reflected off horizontal surfaces, and it is partially polarized. A polarizing filter blocks that polarized light, reducing the glare and making the scene easier to see.

Polarization is a property of all transverse waves, including light and radio waves. Sound waves, which are longitudinal, cannot be polarized. Polarization is used in many technologies. LCD screens use polarizing filters to control the light that passes through each pixel. 3D glasses use polarization to separate the left and right images. Radio antennas use polarization to transmit and receive signals. In chemistry, polarized light is used to study the structure of molecules. Some molecules rotate the plane of polarization, and the amount of rotation reveals information about their structure. Polarization is also used in astronomy to study magnetic fields in space.

Polarization facts

• Definition. Orientation of oscillations in a transverse wave.
• Unpolarized. Oscillates in all directions.
• Polarized. Oscillates in one plane.
• Filters. Block light oscillating in certain directions.
• Applications. Sunglasses, LCD screens, 3D glasses, astronomy.

Polarization is not the same as diffraction. Diffraction is the spreading of waves. Polarization is the orientation of oscillations.